1.) The polymer itself.
1a.) Inherent dangers. Some polymers should never be extruded at home, like PVC.
1b.) Challenges. Some polymers are easier to extrude than others. Some, like PLA, require more prep work in the form of predrying, and may need a direct winder to get good filament tolerances.

2.) Contamination. This is dirt and dust in the source material, which can eventually plug the printer's nozzle (though the Filastruder won't mind as long as the contaminant is smaller than the filament size)
Contamination can be combated with the melt filter I will be releasing in the next 2-3 weeks.

3.) Suitability for 3D printing. No idea how this "p-tex" stuff will print.

tl;dr: the short answer is that the Filastruder should handle it fine, the challenges arise in preparing it for the Filastruder and handling it beyond the nozzle. Keep in mind that virgin material is around $3/lb, so how much is your time worth?

We have considerable waste being thrown out, and it interests me to see if we can dice out laminate remanent 2mm thick flat scraps to create pellets that we could use to make filament for our other product ideas with our 3D printers.

We have both Ski Base materials which are commonly found in two types - Extruded and Sintered.

Extruded bases are made from polyethylene pellets melted down then forced under pressure through a machine which gauges the thickness of the finished material.

Sintering involves crushing polyethylene pellets together under high pressure. This causes them to melt together and fuse, and the resulting sintered material is generally of higher molecular mass and exhibits longer, more uniform molecular chains than extruded material.

It's possible we would also need to distill the Ptex, to remove shop contaminants.  What do you recommend for this?

Has anyone experimented with these types of Ptex(extruded and sintered) already, or has knowledge if Ptex can work with creating good filament?  We will find out soon and report back.